The object of this invention is to satisfy an acknowledged need for a better carton opening knife, in terms of safety and convenience of use and avoiding damage to the contents of cartons during the cutting process.
Among the recognized deficiencies of known prior art knives for this purpose are that they sometimes cut too deeply and damage the contents of cartons in the opening process. The knives in some cases are too small and are constructed so as to be difficult and uncomfortable to hold in the hand. They can also be easily lost. Being formed primarily of metal, the knives tend to corrode and rust.
Another difficulty is that the movable blade guard, if provided at all, is not automatic, and users frequently overlook moving it to the guarding position with the result that the user or his clothing can be cut.
Some prior art knives require the use of a special blade rather than a standard blade, thus increasing cost.
In accordance with the present invention, these and other prior art deficiencies are completely overcome. A carton opening knife is provided which does not have any parts requiring conscious manual movement prior to use. The knife accepts standard safety razor blades. It is safe in that a blade guard or shield springs into place over the blade automatically whenever the knife is not in use. The blade guard retracts automatically whenever the knife is being used. The knife is simple and economical in construction, is convenient and comfortable to grip, resists corrosion in a wet environment, being formed of one piece plastic construction, and includes efficient storage space for spare blades. The blade guard or shield is permanently hinged to the hand grip through a strip which serves as a cover for the blade storage compartment and also forms a cantilever spring for the guard and carries a snap fastener which secures the guard in its operative position.
Other features and advantages of the invention will become apparent during the course of the following description.